The structural and magnetic properties of the small binary clusters
m + n = 7, Y = Ru, Rh, Pd, Pt) were studied through
extensive ab initio calculations, by means of the fully unconstrained version of the
density-functional method, as implemented in the SIESTA code, within the generalized
gradient approximation. The lowest energy state geometries, the chemical ordering, and the
electronic and the magnetic structures were calculated. We found that the lowest energy
geometrical structures for the pure Ru, Rh, Pd, Pt, and Fe heptamers, are a cube without
an apex, a triangular prism capped on a square face, a decahedron, a side capped double
square, and a decahedron, respectively. Starting from these geometries of the pure element
heptamers, we followed the changes in the geometric structure as a function of the
chemical composition. We analyzed all the different chemical arrangements, which depend on
the particular geometry, and magnetic moment orientations, in the whole range of
compositions. In general, there are important modifications to the magnetic moment of the
Y atoms as soon as one of them is substituted by an Fe atom in the cluster. In contrast,
under the same circumstances, the Fe magnetic moment takes values larger than
3 μB and keeps almost this value, insensitive to the
structure, composition and chemical order of the system.
Cohesive Energy Netic Moment Lower Energy State Ground State Structure Triangular Prism
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